Date: Tue, 23 Apr 2013 11:10:01 GMT From: Matthew Rezny <mrezny@hexaneinc.com> To: freebsd-standards@FreeBSD.org Subject: Re: standards/177742: conflict of dd's bs= option with use of conv=sparse Message-ID: <201304231110.r3NBA11i085387@freefall.freebsd.org>
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The following reply was made to PR standards/177742; it has been noted by GNATS.
From: Matthew Rezny <mrezny@hexaneinc.com>
To: Konstantin Belousov <kostikbel@gmail.com>
Cc: bug-followup@FreeBSD.org
Subject: Re: standards/177742: conflict of dd's bs= option with use of
conv=sparse
Date: Tue, 23 Apr 2013 13:00:43 +0200
On Tue, 23 Apr 2013 09:21:23 +0300
Konstantin Belousov <kostikbel@gmail.com> wrote:
> On Thu, Apr 11, 2013 at 05:44:59AM +0200, Matthew Rezny wrote:
> > Looking not just at my problem but the overall situation, it seems
> > the logic in dd_in() does not hold up. The last line, (*cfunc)();,
> > actually invokes the appropriate conversion(s) and then calls
> > dd_out(0). With the simple test on line 361, we will never get down
> > to that call if bs= option is used. Really, to make the code fit
> > the comment, it should probably be something like
> > if ((ddflags & ~(C_NOERROR | C_NOTRUNC | C_SYNC)) == C_BS) {
> > out.dbcnt = in.dbcnt;
> > dd_out(0);
> > in.dbcnt = 0;
> > continue;
> > }
> I do not see why did you changed dd_out(1) to dd_out(0).
>
> Anyway, I am going to commit the following patch, unless I get some
> objection in two-three days:
>
> commit 37664b1393db30d97aa9eefa70360cd550bf9dd9
> Author: Konstantin Belousov <kib@freebsd.org>
> Date: Tue Apr 23 09:18:31 2013 +0300
>
> Literally follow POSIX:
> If the bs= expr operand is specified and no conversions other
> than sync, noerror, or notrunc are requested, the data returned from
> each input block shall be written as a separate output block.
>
> PR: standards/177742
> Submitted by: Matthew Rezny <mrezny@hexaneinc.com>
>
> diff --git a/bin/dd/dd.c b/bin/dd/dd.c
> index 01b66fc..9d0f9b1 100644
> --- a/bin/dd/dd.c
> +++ b/bin/dd/dd.c
> @@ -358,7 +358,7 @@ dd_in(void)
> * than noerror, notrunc or sync are specified, the
> block
> * is output without buffering as it is read.
> */
> - if (ddflags & C_BS) {
> + if ((ddflags & ~(C_NOERROR | C_NOTRUNC | C_SYNC)) ==
> C_BS) { out.dbcnt = in.dbcnt;
> dd_out(1);
> in.dbcnt = 0;
>
On review, I think the dd_out(0) was an oversight. I put the more
precise condition up top but then forgot to put it back to dd_out(1) as
it had been. The one line patch you plan to commit should be effective.
Thank you for taking the time to read my perhaps overly verbose report
on the issue.
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